1. Field of the Invention
The present invention relates to a climbing shoes outsole with good adhesive and non-slip properties and a method for manufacturing the same. More specifically, the present invention relates to a climbing shoes outsole with good adhesive and non-slip properties that has a laminate structure including a butyl rubber as a lower layer of the outsole (side in contact with the ground), and a general-purpose rubber as an upper layer of the outsole (side of the outsole adhered to a midsole or upper), and a method for manufacturing the same.
2. Description of the Related Art
In general, a butyl rubber is widely used for tire inner liners, dustproof materials, automobile tubes and the like due to low gas permeation. Also, a butyl rubber is used as a material for climbing shoes outsoles owing to considerably superior non-slip properties.
Furthermore, as described above, the butyl rubber used as a material for climbing shoes outsoles secures safety against slip and improves grip strength between shoes and the ground during climbing, thereby enhancing wear sensation and comfort. In this regard, materials for climbing shoes outsoles using a butyl rubber with superior non-slip property attract much attention to consumers.
However, companies that manufacture climbing shoes outsoles using a butyl rubber as a base material have a problem of high product defects due to low adhesive properties of butyl rubbers to midsoles or uppers.
In order to solve this problem, in an attempt to improve an adhesive strength through preliminary treatment, the adhesion surface of outsoles is subjected to buffing. However, such a buffing process causes various problems such as production of industrial wastes, noise and product defects caused by buffing.
Also, an expensive CR solvent-type adhesive agent is generally used as an adhesive agent of butyl rubbers. For this reason, problems such as increase in adhesion cost and bad workplace environments resulting from use of excess organic solvent occur.
Accordingly, in an attempt to solve the non-adhesive property, a resin or general-purpose rubber is used in conjunction with a butyl rubber.
However, in general, a butyl rubber has a low compatibility with a resin or a general-purpose rubber, thus having considerably low non-slip property, when used in combination therewith. In particular, when a butyl rubber is adhered to a general-purpose rubber by cross-linking, interfacial de-adhesion generally occurs due to great difference in cross-linking speed between the rubbers and decreased compatibility.
That is, in sulfur crosslinking, a butyl rubber has a considerably low cross-linking speed due to narrow cross-linkage sites. On the other hand, a general-purpose rubber has superior cross-linking activity in a sulfur cross-linking system, thus having a high cross-linking speed, as compared to a butyl rubber. For this reason, there is a difficulty in cross-linking adhesion due to great difference in cross-linking speed between the butyl rubber and the general-purpose rubber upon cross-linking adhesion.
There are conventional methods for adhering resins or rubbers for improving performance of compositions containing a butyl rubber as a base material. For example, a method for adhering a butyl rubber to a resin layer in the process of producing an inner liner for tires by adhering the butyl rubber to the resin layer and irradiating an electric beam thereto, to co-crosslink the butyl rubber and the resin layer is developed. However, in accordance with the method, selection of materials is limited in order to maintain adhesion strength, since adhesion strength between the butyl rubber and the resin layer depends on materials for the resin layer and butyl rubber members.
Meanwhile, as the related art, a method for adhering a resin layer to an adjacent rubber member using an indirect adhesive agent or a highly polar epoxy rubber is used. This indirect adhesive agent or highly polar rubber is expensive and entails use of compounding components having a high glass transition temperature, thus causing cracks or low low-temperature resistance in winter and being unsuitable for shoes to which roughness is repeatedly applied.
Furthermore, Japanese Patent Publication No. 2007-276235 discloses cross-linkage performed by adhering a thermoplastic elastomer resin laminate to a rubber composition member, irradiating an electric beam to the resin-rubber laminate-provided member and performing vulcanization. However, in accordance with this method, disadvantageously, a non-uniform net structure may be formed, heat resistance of rubber layer is decreased, and an interfacial de-adhesion thus occurs when an adhesive layer is not used, since carbon-carbon bonds and sulfur cross-linking are introduced into the rubber layer through electric beam irradiation and vulcanization.